MD5加密实战

为了防止他人直接访问数据库获取用户的用户名和密码从而造成信息外泄，所以我们采用MD5加密。

Main：

package com.jd.test; import java.util.Scanner; import java.util.UUID; import com.jd.tool.MD5Tool; import com.jd.tool.db.DBLink; public class Main { static DBLink db =new DBLink(); public static void main(String[] args) { System.out.println("*********************************"); System.out.println("*\t\t\t\t*"); System.out.println("*\t欢迎使用注册登录系统\t\t*"); System.out.println("*\t\t\t\t*"); System.out.println("*********************************"); while (true) { menu(); } } static void menu() { System.out.println("1、注册");//用户名 密码 确认密码 System.out.println("2、登录");//用户名和密码 System.out.println("3、退出");//System.exit(0); System.out.println("请输入操作，以Enter键结束:"); Scanner scanner = new Scanner(System.in); int option = scanner.nextInt(); switch (option) { case 1:{ System.out.println("注册"); System.out.println("请输入您想要注册的用户名："); String user_name = scanner.next(); System.out.println("请输入您想要注册的密码："); String password = scanner.next(); System.out.println("请再次输入密码："); String repassword = scanner.next(); String sql = "select user_name from user_info where user_name =?"; if(db.exist(sql,user_name)) { System.out.println("抱歉，该用户名已经存在！"); return; } if(!password.equals(repassword)) { System.out.println("抱歉，您两次输入的密码不一致！"); return; } String id = UUID.randomUUID().toString(); password = MD5Tool.encrypt(password); sql="insert into user_info(id,user_name,password)values(?,?,?)"; if(db.update(sql,id,user_name,password)){ System.out.println("注册成功！"); return; } System.out.println("注册失败！"); break; } case 2:{ System.out.println("登录"); System.out.println("请输入用户名："); String user_name = scanner.next(); System.out.println("请输入密码："); String password = scanner.next(); password = MD5Tool.encrypt(password); String sql = "select id from user_info where user_name =? and password =?"; if(db.exist(sql, user_name,password)) { System.out.println("登录成功！"); return; } System.out.println("用户名或密码错误，登录失败！"); break; } case 3:{ System.out.println("退出"); System.exit(0); } default: System.out.println("I'm Sorry,there is not the "+option+" option,please try again."); } } }

DBLink:

package com.jd.tool.db; import java.sql.Connection; import java.sql.DriverManager; import java.sql.PreparedStatement; import java.sql.ResultSet; import java.sql.SQLException; import java.sql.Statement; import org.apache.log4j.Logger; import com.jd.tool.PropertiesTool; public class DBLink { private Logger logger = Logger.getLogger(DBLink.class); /** * 修改功能(防止SQL注入) * *@author Administrator */ public boolean update(String sql,Object...params) { Connection connection =null; PreparedStatement preparedStatement =null; try { connection=getConnection(); preparedStatement = connection.prepareStatement(sql);//含有？占位符的sql for (int i = 0; i < params.length; i++) { preparedStatement.setObject(i+1, params[i]);//为？赋值 } return preparedStatement.executeUpdate()>0; } catch (Exception e) { logger.debug(e.getMessage(),e); } finally { close(preparedStatement,connection); } return false; } /** * 获取数据库连接 * *@author Administrator */ private Connection getConnection() { try { Class.forName("com.mysql.jdbc.Driver");//加载驱动； String username = PropertiesTool.getValue("db.username"); String password = PropertiesTool.getValue("db.password"); String url =PropertiesTool.getValue("db.url"); return DriverManager.getConnection(url, username, password);//获取连接 } catch (Exception e) { logger.debug(e.getMessage(),e); } return null; } /** * 查询功能 * *@author Administrator */ public void select(String sql,IRowMapper rowMapper) { Connection connection=null; Statement statement=null; ResultSet resultSet=null; try { connection=getConnection(); statement = connection.createStatement(); resultSet= statement.executeQuery(sql);//执行sql,将查询的数据存到ResultSet类型的变量中 rowMapper.rowMapper(resultSet); } catch (Exception e) { logger.debug(e.getMessage(),e); }finally { close(resultSet,statement,connection); } } /** * 查询功能 SQL注入 * *@author Administrator */ public void select(String sql,IRowMapper rowMapper,Object...params) { Connection connection=null; PreparedStatement preparedStatement =null; ResultSet resultSet=null; try { connection=getConnection(); preparedStatement = connection.prepareStatement(sql);//含有？占位符的sql for (int i = 0; i < params.length; i++) { preparedStatement.setObject(i+1, params[i]);//为？赋值 } resultSet= preparedStatement.executeQuery();//执行sql,将查询的数据存到ResultSet类型的变量中 rowMapper.rowMapper(resultSet); } catch (Exception e) { logger.debug(e.getMessage(),e); }finally { close(resultSet,preparedStatement,connection); } } /** * 判断是否存在数据 * *@author Administrator */ public boolean exist(String sql,Object...params) { Connection connection=null; PreparedStatement preparedStatement=null; ResultSet resultSet=null; try { connection=getConnection();//获取链接 preparedStatement = connection.prepareStatement(sql);//得到preparedStatement for (int i = 0; i < params.length; i++) { preparedStatement.setObject(1+i, params[i]);//为preparedStatement赋值 } resultSet= preparedStatement.executeQuery();//执行sql,将查询的数据存到ResultSet类型的变量中 return resultSet.next(); } catch (Exception e) { logger.debug(e.getMessage(),e); }finally { close(resultSet,preparedStatement,connection); } return false; } /** * 修改功能(insert,update,delete) * *@author Administrator */ public boolean update(String sql) { Connection connection=null; Statement statement=null; try { connection=getConnection(); statement = connection.createStatement(); int result = statement.executeUpdate(sql); return result>0; }catch (Exception e) { logger.debug(e.getMessage(),e); }finally { close(statement,connection); } return false; } /** * 释放资源 * *@author Administrator */ private void close(Statement statement, Connection connection) { try { if(statement!=null) { statement.close(); } } catch (SQLException e) { logger.debug(e.getMessage(),e); } try { if(connection!=null) { connection.close(); } } catch (SQLException e) { logger.debug(e.getMessage(),e); } } /** *释放资源 * *@author Administrator */ private void close(ResultSet resultSet,Statement statement, Connection connection) { try { if(resultSet!=null) { resultSet.close(); } } catch (SQLException e) { logger.debug(e.getMessage(),e); } close(statement, connection); } }

IRowMapper:

package com.jd.tool.db; import java.sql.ResultSet; public interface IRowMapper { void rowMapper(ResultSet rs); }

MD5Tool:

package com.jd.tool; import java.math.BigInteger; import java.security.MessageDigest; public class MD5Tool { public static String encrypt(String password) { byte[] bytes = null; try { MessageDigest messageDigest = MessageDigest.getInstance("MD5"); messageDigest.update(password.getBytes());//加密 bytes = messageDigest.digest();//获得加密结果 } catch (Exception e) { e.printStackTrace(); } String result = new BigInteger(1, bytes).toString(16);// 将加密后的数据转换为16进制数字 // 生成数字未满32位，则前面补0 for (int i = 0; i < 32 - result.length(); i++) { result = "0" + result; } return result; } }

PropertiesTool:

package com.jd.tool; import java.io.IOException; import java.io.InputStream; import java.util.Properties; public class PropertiesTool { private static Properties properties = new Properties(); static { InputStream inputStream = PropertiesTool.class.getClassLoader().getResourceAsStream("db.properties");//将db.properties变为javaIO流对象 try { properties.load(inputStream); } catch (IOException e) { e.printStackTrace(); } } public static void main(String [] ages) { } public static String getValue(String key) { return properties.getProperty(key); } }

db.properties:

db.username=root db.password=root db.url=jdbc:mysql://localhost:3306/test

log4j.properties:

# DEBUG\u8BBE\u7F6E\u8F93\u51FA\u65E5\u5FD7\u7EA7\u522B\uFF0C\u7531\u4E8E\u4E3ADEBUG\uFF0C\u6240\u4EE5ERROR\u3001WARN\u548CINFO \u7EA7\u522B\u65E5\u5FD7\u4FE1\u606F\u4E5F\u4F1A\u663E\u793A\u51FA\u6765 log4j.rootLogger=DEBUG,Console,RollingFile #\u5C06\u65E5\u5FD7\u4FE1\u606F\u8F93\u51FA\u5230\u63A7\u5236\u53F0 log4j.appender.Console=org.apache.log4j.ConsoleAppender log4j.appender.Console.layout=org.apache.log4j.PatternLayout log4j.appender.Console.layout.ConversionPattern= [%-5p]-[%d{yyyy-MM-dd HH:mm:ss}] -%l -%m%n #\u5C06\u65E5\u5FD7\u4FE1\u606F\u8F93\u51FA\u5230\u64CD\u4F5C\u7CFB\u7EDFD\u76D8\u6839\u76EE\u5F55\u4E0B\u7684log.log\u6587\u4EF6\u4E2D log4j.appender.RollingFile=org.apache.log4j.DailyRollingFileAppender log4j.appender.RollingFile.File=D://log.log log4j.appender.RollingFile.layout=org.apache.log4j.PatternLayout log4j.appender.RollingFile.layout.ConversionPattern=%d [%t] %-5p %-40.40c %X{traceId}-%m%n